Remember, the -2.9% annualized drop in Q1 GDP was largely driven by a drop in exports which "subtracted 150 bps from overall output and a slower pace of inventory accumulation, which lopped another 170 bps off of growth," Deutsche Bank analysts pointed out.

So it was expected that an improvement this time around might provide a boost to GDP. Turns out, the better headline number in May masked an interesting detail, namely that most of the improvement was tied to a drop in the petroleum deficit.

"While the real goods deficit shrank, it was less than what we had penciled in as a rebound following a large widening in April. As a result, this report suggests that net exports continued to act as a drag on real GDP growth in the second quarter after providing a -1.5pp contribution in Q1."

Barclays sees US Q2 GDP tracking down 0.5 percentage points to 2.7%, after the "May real goods balance narrows less than forecast."

Jana McTigue at Pantheon Macroeconomics also points to this and adds, that "even if we assume better export numbers in June, the quarter as a whole looks very unbalanced, with core exports likely to rise at a 6% annualized rate while imports are heading for 22%."

"Net foreign trade therefore will be a drag on Q2 GDP growth, subtracting perhaps as much as 0.7 percentage points from growth. H2 should be better, but right now these numbers are grim," McTigue writes.